He built a school in Westchester, for 'gifted students'. People with mutant powers, like me and my friends. He trained us to user our powers to help people. He trained us to control them - if they could be. If not, he found other ways to help us.
... it sounds idealized, but the truth is that he made us into soldiers for the mutant cause. That's what we were, but I never minded it. He had a dream - he wanted us to live peacefully with humans that had no powers.